James fitzgerald



JAMES l FITZGERALD, OE BROOKLYN, NEW YORK.

Leners PatemN. 100,612, dated Mam 8,1870.

`BALANCZE! SLIDE-VALVE.

(The Schedule referred to in these Letters Patent and making part of the same.

l'o all whom it may concern:

Be it known that I, J AMES FITZGERALD, of Brooklyn, inthe county of Kings, and State of New York, have invented anew and useful Improvement in Balanced Slide-Valve; and I do hereby declare that the following is a full, clear, and exact description thereof',

which will enable others skilled inthe art to make and use the same, reference being had to the accompanying` drawing forming part o f this specification.

This invention rela-tes to a new andl useful improve- .ment in mode of operating the slide-valves of steamengines, whereby the same are balanced or nearly balanced; and 1 y e It consists in the construction and arrangement hereinafter described. f "In the accompanying drawing- Figure 1 represents a vertical section of the arrangement through the line a: a: of iig. 2.

`Figure 2 is a top or plan view. l

Similar letters of reference indicate corresponding parts,

A is the steam-chest.

B is the slide-valve.

C is a piston in the back of the slide-valve.

D represents a rail, on one edge of which there is a .cogged rack, E.

F F represent rolls, upon one end of which are pinl ions G Gr, which engage with the rack E, as seen` in the drawing. The other ends of the rolls are flanged and serve to guide the rolls on the rail.

The rail D rests on the lugs H H.

I is a plate which rests on therolls.

J is the piston-rod, which passes up through the rail D, which rail is'slotted, as seen at D', so that the rod may move back and forth with the valve.

The rod passes up through the plate I and the piston is suspended therefrom by means of the pin K,

which passes through a hole in thetopof the rod.

The pressure of the steam upon the slide-valves is diminished in proportion to the area of the'piston.

The pressure on the piston is supported by the rollers which traverse freely back and forth on the bearingrail D. The rack and pinious serve tomaintaiu the rollers in proper position.

It will be seen that the slide-valve is left entirely free, with sufficient pressure upon itto keep it fairly on its seat.

The' piston is designed to work steam tight/in the valve, the lower side of it receiving the pressure of the exhaust at every stroke of the engine. The movement of the piston in the valve is of course very slight, it being only suilicient to compensate for the slight wear of the valve and of the rollers.v

Having thus described my invention,

' I claim as newfand desire to secure by Letters Patent- In combination with a slide-valve, the pistou C, rail D, rollers F F, with the rack E, pinions G, and plate I, arranged to operate substantially as and for the purposes herein shown and described.

AThe above specific-ation of my invention signed by me this 12th day of November, 1869. v

JAMES FITZGERALD.` lVitnesses:

GEO. W; MABEE, ALEX. F. ROBERTS. 

